标题：Empty pericarp7 encodes a mitochondrial E-subgroup pentatricopeptide repeat protein that is required for ccmF(N) editing, mitochondrial function and seed development in maize
作者：Sun, Feng;Wang, Xiaomin;Bonnard, Geraldine;Shen, Yun;Xiu, Zhihui;Li, Xiaojie;Gao, Dahai;Zhang, Zhonghang;Tan, Bao-Cai
作者机构：[Sun, F] Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, School of Life Sciences, Shandong University, Jinan 更多
通讯作者地址：[Tan, BC]Shandong Univ, Sch Life Sci, Key Lab Plant Cell Engn & Germplasm Innovat, Minist Educ, Jinan 250100, Peoples R China.
来源：The Plant Journal
关键词：maize;empty pericarp7;cytochromec maturation;mitochondrion;seed development
摘要：RNA editing, converting cytidines (C) to uridines (U) at specific sites in the transcripts of mitochondria and plastids, plays a critical role in organelle gene expression in land plants. Recently pentatricopeptide repeat (PPR) proteins were identified as site-specific recognition factors for RNA editing. In this study, we characterized an empty pericarp7 mutant (emp7) in Zea mays (maize), which confers an embryo-lethal phenotype. In emp7 mutants, mitochondrial functions are seriously perturbed, resulting in a strikingly reduced respiration rate. Emp7 encodes an E-subgroup PPR protein that is localized exclusively in the mitochondrion. Null mutation of Emp7 abolishes the CU editing of ccmF(N) transcript solely at position 1553. CcmF(N) is coding for a subunit of heme lyase complex in the cytochromec maturation pathway. The resulting PheSer substitution in CcmF(N) leads to the loss of CcmF(N) protein and a strikingly reduced c-type cytochrome. Consequently, the mitochondrial cytochrome-linked respiratory chain is impaired as a result of the disassembly of complexIII in the emp7 mutant. These results indicate that the PPR-E subgroup protein EMP7 is required for CU editing of ccmF(N)-1553 at a position essential for cytochromec maturation and mitochondrial oxidative phosphorylation, and hence is essential to embryo and endosperm development in maize.